Condenser microphone



Nov. 30; 1943. E. GERLAC H 2,335,662

CONDENSER MICROPHONE Filed July 15, 1939 /0 ,3 Z5 5 J 6 m I I fiw M M 3 -27 y I I E 2 INVENTOR. ERW/N GERLACH BY ATTORNEY.

- mospheric pressure.

Patented Nov. 30, 1943 CQNDENSER WCBOPHONE Erwin Gerlach, Berlin, (Germany; vested in the Alien Property @nstodian Application July 15, 1939, Serial No. 284,648 in Germany July 25, 1938 (m. Et -=66) ll (Claims.

The present invention is concerned with a method for processing and mounting condenser-- typemicrophones and the like.

In processing condenser or electrostatic microphones special care must be taken so that no dust will be able to enter into the microphone. The distance separating the electrodes or plates amounts to only a few microns (thousandthsof one millimeter); hence, any particles of dust that may get between the plates or electrodes are liable to cause serious troubles.

It has been suggested in the art to assemble condenser microphones only in regions or places practically free from dust and to do such work only in tiled workshops, or else to take care so that the dust content of workshops is reduced to the lowest possible degree.

Now, this invention discloses another working method and procedure, namely, to effect the assembly and mounting inside a closed box or container into which purified air is introduced under pressure with the result that the pressure prevailing within the box is always above the at- Further objects of the invention consist in means adapted to cleaning and mounting or processing inside this box.

The appended drawing illustrates an exemplified embodiment of the invention. Fig. l is a top view of the mounting box or enclosure occorcling to the invention, with the cover thereofbeing removed, while Fig. 2 is a side'view in section.

On its top the box i has a glass cover plate 2. Through a lateral wall of the box is introduced the handle or stem 3 of tongs or pliers i, there i being an articulation or swivel joint ii whereby the tongs t may be moved in any desired direction. In other Words, the said joint permit-s motion in the direction of the rod 3 as well as movement in any lateral angular sense. Gpening and closing of the jaws of the tongs is effectedby the aid of the handle 3' being subject to the pressure of a spring. If by pressure exerted upon the grip or handle 8, the spring t is compressed, this causes opening of the tongs t. End 8 of rod 3 is fitted with a member adapted'to co-operate with the clutch it of motor it.

In the longitudinal side or wall of the box is a look through which the parts forming the microphone may be brought into the interior of the box. The said lock comprises a U-shaped holder member H, one half of which projects into the box, while theother half extrudes from the box. Shiftablein the said holder it. is a.

it in the lateral wall of the box 9. Provided in the said drawer i2 is areceiver or receptacle it for a microphone part. In the box, itself, is a nozzle M which has a guard rim H5. The said nozzle is is connected with a pump it mounted below the box, while a fluid storage tank 31 is connected, on the one hand, with the pump it, and, on the other hand, with an outlet inside the guard rim l5. Laterally in reference to the box is a drying chamber lit in which is a platform is with several receptacles 2% adapted to accommodate microphone parts. The platform is is revoluble about a pivot or axis it by the aid of a crank 22. Heating of the chamber it is effected by hot water, heating being preferably by electricity.

Super-atmospheric pressure is produced inside the box l by the aid of a blower 23; the air handled.- by this blower 23 being always carefully purified.

0n top of the box is a container it for varnish fitted with a dripper nozzle 25, a handle 25 being provided to open and close the said nozzle.

Now, the operation of this apparatus is as follows:

The drawer I2 is withdrawn from the box i to an extent so that a microphon part may be placed into its receptacle l3. While this is being done, the drawer i2 shuts the opening provided for it in the box l. The drawer l2 thereupon is pushed into the box i to a depth so that the receptacle iii comes to lie entirely inside the box. By compression of the spring 6 by the agency of the handle it the tongs d are opened. By the aid oi the latter, th microphone part placed in the receptacle it of the drawer i2 is taken out. By shifting the handle or rod 3, the microphone part (designated by M in the drawing) is placed over the nozzle id, while the rod is being turned, until the microphone part M has been thoroughly rinsed all around by the liquid or fluid issuing from. the nozzle, preferably quick-drying fluid such as carbon tetrachloride. Thereupon, the tongs with the part M are withdrawn, the clutch members 8 and 9 are engaged, and the motor to is out in circuit. As a result the microphone part id is rapidly rotated and the rinsing or cleans ing fluid is thrown ofi by centrifugal action and rapidly volatilized. A cylinder T5 is provided to gather the spa'ttered liquid. The said cylinder has a rod 28 whereby the cylinder may be shifted. As soon as part M is dry it is placed underneath the nozzle 25 and a drop of lacquer is allowedto fall upon the under face and the top face of the drawer 52 which shuts the opening provided for 55 diaphragm. Next rod 3 is again engaged with the motor In and by rotating part M inside the protective cylinder 21 the lacquer is caused to spread all over the diaphragm, while the surplus is allowed to spatter. Next part M is laid into receptacle 20 or the platform or circular disc I! and brought into the drying chamber i8 by rotating the crank 22. While the bottom or back part of the microphone is being dried in the drying chamber I8, the top plate of the microphone is brought through the lock and drawer l2 into the box I in a way as hereinbefore described, gripped by tongs I, cleansed by the nozzle, centrifuged inside the protectivecylinder or casing 21 and thereupon placed also into receptacle 20 of the platform l9 and then brought into the drying chamber l8. After both parts have been dried, the bottom or back part is laid into the receptacle iii of drawer l2, the top 'isfitted upon the bottom or back part so that both members are fitted in a fairly hermetic way upon each other and are then withdrawn by way of the lock and drawer l2 from the box I. Final assembly of the microphone parts may then be completed outside the box.

Instead of a single lock arrangement ll-l2, another such'lock could be provided, say, in the neighborhood of the drying chamber it, together with other tongs so that the dried back and top members are placed down upon the drawer of this lock'and thereby removed from the box.

What is claimed is:

1. In the art of processing electrostatic microphone elements, the steps of, passing an individual element into a closed chamber, clamping the element so that it may be handled from a position externally of the chamber, spraying the element with a cleaning fluid, rotating the element thereby to dry the element, applying a protective coating to one surface of the element, placing the element in a heated portion of the chamber which is substantially se arated from the remainder of the chamber thereby to dry the protective coating, placing another element into the chamber and treating the element to the steps of spraying and drying and subsequently to the heating step all in a manner similar to the treating of the first-mentioned element, interfltting the two elements, and removing the associated elements.

2. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, means for passing said object through at least one of the walls of said chamber, means for changing the physical position of said object within said chamber from the outside,

fluid means within said chamber for cleaning the object, and means located without said chamber and passing through its walls for drying said object within the chamber after cleaning.

3. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, an air-tight door for passing said object through at least one of the walls of said chamber, means for changing the physical position of said object within said chamber from the outside, fluid means within said chamber for cleaning the object, and means located without said chamber and passing through its walls for drying said object within the chamber after cleaning.

4. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, an air-tight door for passing an fluid means within said chamber for cleaning'said object, means for changing the physical position of said object within said chamber from a position outside, and means within said chamber for drying said object after cleaning.

5. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, an air-tight door for passing an object through at least one of the walls of said chamber, a nozzle adjacent said door for passing fluid means within said chamber for cleaning said object, a movable member for changing the physical position of said object within said chamber from a position outside, and means within said chamber for drying said object after cleaning.

6. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, an air-tight door for passing an object through at least one of the walls of said chamber, a nozzle adjacent said door for passing fluid means within said chamber for cleaning said object, .a movable member passing through another wall of said chamber .for changing the physical position of said objectwithin said chamber from the outside, and means located outside said chamber and coupled to said movable member for drying said object after cleaning by centrifugal action within said chamber.

7. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, an air-tight door for passing an object through at least one of the walls of said chamber, a nozzle adjacent said door for passing fluid means within said chamber for cleaning said object, a movable member passing through another wall of said chamber for changing the physical position of said object within said chamber from the outside, means located outside of said chamber and coupled to said movable member for drying said object after cleaning by centriiugal action within said chamber, means passing through said chamber for applying a protectivecoating to the surface of said object, and a second means for drying said protective coating on said object within said chamber.

8. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the, outside, an air-tight door for passing an object through at least one of the walls of said chamber, a nozzle adjacent said door for passing object through at least one of the walls of said v fluid means within said chamber for cleaning said object, a movable member passing through another Wall of said chamber, tongs secured to an end of said movable member for moving said object from one position to another within said chamber, means for applying a protective coating to the surface of said object, and means for gzying said protective coating within said cham- 9. 'Apparatus for processing anobject comprising a chamber maintained at a pressure higher 'than'the outside, a transparent cover for said chamber, means for passing said object through at least one of the walls of said chamber, means for changing the physical position of said object within said chamber from the outside, fluid means including a nozzle located within saidchamber for cleaning the object, means located without said chamber and passing through its walls for drying said object within said chamber after cleaning, a tank located outside said casing for storing a lacquer and a drip nozzle for coating the surface of said object, means passing through a wall of said chamber for connecting said tank to assaeoa 3 said drip nozzle to apply said coating to said object, and means for drying said coating within said casing.

10. Apparatus for processing an object comprising a chamber maintained at a pressure higher than the outside, a transparent cover for said chamber, means for passing said object through at least one of the walls of said chamber, means including a movable shaft for changing the physical position of said object within said chamber from the outside, fluid means including a nozzle located within said chamber for cleaning the object, means for drying said object within said chamber including a motor and a clutch which is located without said' chamber, said movable shaft passing through the walls of said chamber and coupled to said clutch, a tank located outside said casing for storing a fluid for coating the surface of said object, means passing through a wall of said chamber for ap;,' plying said coating to said object, and means for drying said coating within said casing.

11. Apparatus for processing electrical elements comprising a chamber maintained at a pressure higher than the outside, a transparent cover for said chamber, means for passing said electrical elements through at least one of the walls of said chamber, means forchanging the I ments within said chamber after cleaning, a tank located outside said casing for storing a fluid for coating the surface of said electrical elements,

means passing through a wall of said chamber for applying said coating to said electrical. elements, and means for drying said coating within said casin ERWIN GERLACH. 

